Brodhead Pietenpol Association

Original Posted By: "D. Engelkenjohn"
Gene,CAM 18 dated 12/15/59 says in 18.30-4 "Brazing may be used for repair to primaryaircraft structures only if brazing was originally approved for the particularapplication....." meaning the metals would need to be compatible.....Chris bobka________________________________________________________________________________Date: Wed, 25 Jun 2003 17:33:23 -0500

Original Posted By: "w b evans"
Walt,I have used your system over the years on wooden props and a tip I wouldadd, the back side of the blade on mine were always a dull black. I wouldmist dull black paint from a spray can to help with the balance. Workedgreat. Another tip, on the leading edges we have found that electrical tapeworks great for protective covering. It is installed while on the parallelsteel pieces.Going one step farther, we have machined a cone that fits into the prop hub.Putting a large nail with the tip ground to a sharp point in a vice thenplacing the cone on the nail and placing the prop on the cone. Then we useda small circular Sears fluid filled center finder. This quickly shows ifone blade is off weight. It is placed in the center of the prop hub. Usingthis along with the parallel steel pieces method, one can get a wooden propbalanced quite easily.I hope I have explained it with acceptable clarity. Just thought I wouldadd this for food for thought.Alex Sloan----- Original Message -----

Original Posted By: "Christian Bobka"
At the risk of getting even more snyde responses, let me point out that thenumerous statements that have been forwarded merely say that brazing is notacceptable for structural REPAIRS. That is not the same thing as sayingthat 4130 should NEVER be brazed.You know, I am not an idiot, nor am I new to aviation maintenance andaircraft building/rebuilding. I have stepped up on one of our member'sbehalf to question what has become a commonly accepted statement without anyproof behind it.The only alleged source for a PROHIBITION against brazing 4130 for ANYapplication is the guy (whose name I have now forgotten) who contributed tothe revised 43.13. Any others????If it is such a stupid question, why can't I see more sources?Gene----- Original Message -----

Original Posted By: "Craigo"
Subject: Re: Pietenpol-List: Wood prop balancingIn a message dated 6/25/03 7:54:05 AM Central Daylight Time, Michael.D.Cuy(at)grc.nasa.gov writes:>Mike,In A&P school they taught us that 'Horizontal Balance' is when the tips point up and down, and 'Vertical Balance' is when the tips are to the right and left...go figure. The prop is balanced off the center hole, and tracked off theflange faying surface. The way I balance the prop is with a mandrill through the center hole, set on parallel steel strips, which are edge mounted in a wood box that is shaped like a 'miter box'. Level the box, check the prop this way, that way, flipit over and check in both directions again, to make sure you locate the heavy blade. Add varnish to the flat side (called the 'Face', because it 'faces thepilot) of the light blade, or add varnish to a low area on the airfoil. Problem is I can't check the horizontal balance - tips going up and down. I likethe method that John Dilatush mentioned, but I don't like the thought of drilling hole and adding lead. It would also be necessary to check the prop usingthe flange faying surface. I'm now looking for one of these old tire balancers. I think one of the major sources of vibrations is when the blade is out of track. Wood props DEFINITELY contort when nicks allow moisture to enter thewood, or the prop is not stored with the blades in the horizontal position. When checking track, make sure the end play in the crank is pushed in the samedirection, and that you use a similar location on each tip. Shim with a piece of paper. According to AC43-13, wood props are tracked so they are within1/8" of each other, but I prefer making them track within 1/16". Another quick check would be to lay the prop on the table, and check the prop with a straight edge all the way from tip to tip, passing through the exact center of the center hole, and see if the straight edge lies in the samepart radius of the prop tips. This check would determine if one of the bladeshas moved in the plane of rotation. When building a prop, it is very important to make the shape of the airfoil at each blade station match exactly on both blades. Hopefully a prop thatis store bought already matches the airfoil shapes.Chuck________________________________________________________________________________

Original Posted By: John_Duprey(at)vmed.org
I'm now looking for one of> these old tire > balancers. Rick and others -Harbor Freight has a vey good tire balancer for about$40 +/- (bought it some months ago, but don't rememberthe price). It has a truncated cone with a bubblelevel in the top, very sensitive. We use it on therace car tires, as well as our prop.CraigLake Worth, FLBakeng Duce NX96CWPeoplePC: It's for people. And it's just smart. http://www.peoplepc.com ________________________________________________________________________________

Original Posted By: Gene Rambo
Gene,I am looking for more info on this.Chris Bobka----- Original Message -----